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United States Department of Agriculture

Agricultural Research Service

Title: Soil Carbon and Cesium-137 Relationships in a Small Agricultural Watershed

Authors
item Ritchie, Jerry
item McCarty, Gregory

Submitted to: Abstract of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: July 30, 2001
Publication Date: October 22, 2001

Technical Abstract: Scientific, political, and social interest have developed recently in the concept of using agricultural soils to sequester carbon. The problem is to determine the patterns of soil erosion and redeposition on the landscape and to relate this to soil carbon patterns. Cesium-137 has been used to estimate soil erosion patterns and redeposition patterns at the field level. The purpose of this study was to determine the relationship between Cs-137, soil erosion, and soil carbon distribution. Profiles of soils from an upland area and an adjacent riparian area were collected in 5 cm increments and the concentrations of Cs-137 and carbon were determined. Cs-137 was uniformly mixed in the upper 15-20 cm of upland soil profiles. Carbon content of the upland soil profiles ranged from 0.5 to 1.9 % with an average of 1.2 ñ 0.4 % in the 0-20 cm layer while carbon below this tilled layer (20-30 cm) ranged from 0.2 to 1.5 % with an average of 0.5 ñ 0.3 %. Total carbon was 2.66 kg/m^2 and 3.20 kg/m^2 in the upper 20 cm and upper 30 cm of the upland soils, respectively. Carbon content of the 0-20 cm layer in the riparian area ranged from 0.9 to 33.6 % with an average 5.0 ñ 0.9 %. Carbon content below 20 cm ranged from 0.6 to 15.4 % with an average of 5.0 ñ 3.9 %. Total carbon in the upper 20 cm of the riparian profile was 10.1 kg/m^2 and 15.0 kg/m^2 in the upper 30 cm of the riparian profiles. Carbon and Cs-137 content (Bq/g) in the soils were strongly correlated (r=0.81). Carbon content of the 0-20 cm layer was higher (1.4 ñ 0.3%) in areas of soil deposition than carbon content (1.1 ñ 0.3%) in areas of soil erosion. These data suggest that measurements of Cs-137 in the soils can be useful for understanding carbon distribution patterns in surface soils.

Last Modified: 4/17/2014
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